Three B.C. environmental groups say their polling finds 79 per cent of people in the province support a ban on oil tanker traffic in B.C.'s inside coastal waters, and 38 per cent say the issue will influence how they vote Monday.

The poll was commissioned by Dogwood Initiative, West Coast Environmental Law Association and Living Oceans Society and carried out by Strategic Communications.

Oil tankers already ply the Georgia Strait, loading in Vancouver's harbour by connecting to the Kinder-Morgan pipeline that carries crude from Alberta's oil sands -- an output Kinder-Morgan predicts will double.

However, another controversial pipeline proposed by Enbridge and backed by the Harper Conservative government and the B.C. Liberal government would connect the oil sands to the northern B.C. port of Kitimat for tanker traffic to Asia and other destinations.

Enbridge vice-president Steven Greenaway has stated, "If we did not believe that the movement of petroleum goods could be done safely, either in a pipeline or by vessel, we would not have proposed the project."

Opponents say such oil tanker traffic would endanger B.C.'s northern coastline, and point to a tanker traffic moratorium they say has been in place for decades.

In 1971 former Liberal environment minister David Anderson and others successfully sued the U.S. government to prevent tankers laden with Alaskan oil from endangering the Canadian coastline. Congress then took it up and the two countries entered into an understanding that U.S. oil vessels would stay 70 nautical miles offshore.

In 2007 Anderson told The Tyee that in 1972, when he was Liberal environment minister, he convinced prime minister Pierre Trudeau to go a step further and ban offshore oil drilling along B.C.'s coast, and to apply the U.S. tanker ban to other oil carriers as well, a practice that has been maintained by every federal government since.

The Conservatives say no such moratorium exists.

The poll results are "a clear indication that oil tankers will be a defining election issue on Monday," said Eric Swanson, No Tankers director for the Dogwood Initiative. "We've been talking to thousands of British Columbians and their voice is clear: this is our coast and our decision."

The poll, says a press release announcing its results, surveyed 830 adult British Columbians between April 14 and April 18. It indicates that 65 per cent of Conservative voters support a ban on oil tanker traffic, along with 83 per cent of Liberal voters and 88 per cent of NDP voters. The poll's findings, based on the sample size, are said to be accurate within a margin of error of 3.4 per cent, 19 times out of 20.

The platform of the federal Liberals commits to a legislated ban on all oil tanker traffic on B.C.'s north coast, and the NDP and Green party have also said they support a ban of oil tankers off B.C.'s north coast.

The Conservatives have said they will not ban oil tankers.

Environmental groups have mobilized in B.C. to keep the issue before B.C. voters. According to Emma Gilchrist of the Dogwood Initiative, the group has more than 100 election volunteers making phone calls and going door to door in strategic ridings and has placed more than 25,000 automated calls into five ridings.

The group last week hosted two "telephone town halls" which called 11,000 people in Esquimalt-Juan de Fuca and 14,000 in North Vancouver and invited them to stay on the line to listen and participate in a discussion about the tanker traffic issue. Gilchrist says 6,000 people participated. She says the campaign has identified and is communicating with 65,000 No Tankers supporters in ridings around the province.

David Beers is editor of The Tyee.